Palm activated drug delivery device

ABSTRACT

Disclosed is a device for the parenteral delivery of a medication, such as a drug. The device includes upper and lower housings in which the upper housing is configured to move relative to the lower housing as a result of application of an external force to permit the user of the device to control the rate at which the drug is administered.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/939,416, filed Nov. 12, 2015, which is a divisionalapplication of U.S. patent application Ser. No. 12/905,572, filed Oct.15, 2010, which claims priority to U.S. Provisional Application Ser. No.61/361,983, filed Jul. 7, 2010, and U.S. Provisional Application Ser.No. 61/252,378, filed Oct. 16, 2009, the disclosures of all of which arehereby incorporated by reference as if set forth in their entiretyherein.

FIELD OF THE INVENTION

The invention generally relates to methods and devices for parenteraldrug delivery. The devices provide for assisted manual drug deliverywith confirmation of completion of the drug delivery process. Thedevices provide a system with improved safety and ease of use andaudible, or other forms of, feedback to the user to indicate when drugdelivery is in process, completed, or both, to avoid one or both ofincomplete dosing and wasted medication as well as to provide a systemwith improved safety and ease of use.

BACKGROUND OF THE INVENTION

For many years, an accepted method for parenteral drug delivery has beenthrough the use of syringe and needle. The syringe contains a quantityof a drug sold either in a pre-filled syringe or introduced into asyringe by drawing the drug into a syringe from a vial or othercontainer. Syringes have been widely accepted due to their lowmanufacturing cost and simple, effective design. For the user, however,syringes and needles have a number of drawbacks.

One drawback is that many patients have a fear of needles. In instancesin which self-medication is required, such as those requiring multiple,daily injections, patients may not administer their medication accordingto their prescribed regimen due to the fear of needles, the pain that isoften associated with an injection, the dexterity that is required toproperly administer a drug via needle and syringe or other, similarfactors. For some, that have their vision, dexterity, or awarenessimpaired, self-administration via needle and syringe may presentadditional difficulties that can prevent them from receiving theirrequired medication.

There also are safety and disposal concerns associated with needles andsyringes not only for the patient, but for those around them, that mayresult from contaminated needles, accidental punctures,cross-contamination, and the like, in addition to the social stigmaassociated with a needle and syringe drug-treatment regimen. Despitethese drawbacks, however, many patients are encouraged to use needlesand syringes to deliver their medication due to the ability to controlinsertion of the needle and the speed of the drug delivery when theplunger in the syringe is depressed and, therefore, control theirperception of pain and discomfort associated with this type of druginjection.

Several advances have been made over the years to help facilitateself-administration of medication. Such advances include smaller needleswith improved tip-geometry to reduce the pain. Safety syringes thatencase the needle before, after, or before and after use have been usedto minimize concerns over accidental punctures with needles. Improvedergonomics in syringe design, as well, have been promoted to reduce thedexterity required to accurately and safely self-administer medicationvia needle and syringe. Pre-filled disposable devices having aform-factor similar to that of a pen were developed to improve dosingaccuracy, and auto-injectors have been used to hide the needle from thepatient to reduce fears and safety concerns either by retracting theneedle or placing a shield around the needle.

While such advances have improved needle and syringe based drugdelivery, ergonomic designs, pens, and auto-injectors all retain asubstantial similarity to the original needle and syringe concept, thuslimiting their acceptance by patients who need to self-administer theirmedication. Current systems employ a form factor that suggests thecommon “grab and stab” injection technique, wherein the user grips thedevice in the palm and places the thumb over an activation button.

Current auto-injectors transfer control of drug delivery into the bodyto a mechanical system. Because such a system is highly dependent on thespecific mechanical design of the auto-injector, patients may requirespecialized training to use the device and still risk inaccurate dosing.This situation is highly problematic when delivering very expensivedrugs that might only be administered on a weekly or even moreinfrequent basis.

The typical method of use of current auto-injectors includes the patientholding the device against the skin for several seconds while the deviceis in the process of delivering medication. Many users, and the elderlyin particular, may experience fatigue in their arm or hand causing themto exert uneven pressure of the device against the skin, or they mayremove the device prematurely. Either situation can result in inaccuratedosing, wasted medication, increased discomfort, and the like. Under anyof these circumstances, the current devices and methods that include, orevolved from, the traditional syringe and needle system haveshortcomings that compromise the efficacy of a prescribed drug regimen.

Finally, as with any health-care related device or service, the cost ofany frequently used component of a treatment regimen must be considered.While providing drugs in vials that are used to fill empty syringes at,or about, the time of a patient's medication may provide the leastexpensive solution, it adds an additional opportunity for waste or lossof an expensive drug. If that drug requires refrigeration, it mayexperience degradation each time it is removed and reinserted into therefrigeration device before and after filling the syringe, which canlead to less than expected drug efficacy if the vial contains a quantityof drug that is delivered over a long period of time. While pre-filledsyringes offer an advantage in both reliability and convenience, suchdevices still have the inherent drawbacks previously recited.

With devices such as pre-filled auto-injectors, the device is mostcommonly manufactured for use with a wide variety of medications, but istailored to no one medication. Because such devices rely on mechanicalsystems employing springs to control the injection rate of the drug,many drugs of different viscosity or that require refrigeration andchange viscosity appreciably as a result of temperature change, may bedelivered too quickly or too slowly for the predetermined spring-forceof the auto-injector design. In many instances, too low a spring forcemay result in incomplete drug delivery, removal of the device beforecompletion of the delivery, or excessive pain and discomfort to the userresulting from a prolonged period during which the injection device isinserted into the body. Too high a spring force, however, can result indrug delivery that is so rapid that it degrades the drug, or may causeinjection force pain to the patient caused by rapid delivery of anacidic drug or by inducing a pressure gradient under the skin or in avein.

Thus, there are many opportunities for advancement in the field ofepisodic, parenteral drug delivery that could overcome “needle-phobia”,reduce pain to the patient, and increase the safety, reliability andefficacy of many drug treatment regimen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of an embodiment of the present invention.

FIG. 1B is a side view of the embodiment of FIG. 1A after cap removal.

FIG. 1C is a side view of the embodiment of FIG. 1B after depression ofthe interlock button.

FIG. 1D is a side view of the embodiment of FIG. 1C after the needleguard has been retracted, exposing the needle.

FIG. 2A is a side view of the embodiment of FIG. 1D during druginjection.

FIG. 2B is a side view of the embodiment of FIG. 2A upon completion ofdrug injection.

FIG. 2C is a side view of the embodiment of FIG. 2B after the needleguard has been extended, concealing the needle,

FIG. 3 is a depiction of an exploded view of the embodiment of FIG. 1A.

FIG. 4 is a depiction of a cross-sectional view of the embodiment ofFIG. 1A.

FIG. 5 is a depiction of a partial cross-sectional view of a portion ofthe embodiment of FIG. 1A, depicting a latch.

FIG. 6 is a depiction of a partial cross-sectional view of a portion ofthe embodiment of FIG. 1A, depicting a latch.

FIG. 7 is a depiction of a cross-sectional view of the embodiment ofFIG. 2A.

FIG. 8 is a depiction of a cross-sectional view of the embodiment ofFIG. 2B.

FIG. 9 is a depiction of a cross-sectional view of the embodiment ofFIG. 2C

FIG. 10A is a side view of another embodiment of the present invention.

FIG. 10B is a side view of the embodiment of FIG. 10A after cap removal.

FIG. 10C is a side view of the embodiment of FIG. 10B after the needleguard has been retracted, exposing the needle.

FIG. 11A is a side view of the embodiment of FIG. 10C during druginjection.

FIG. 11B is a side view of the embodiment of FIG. 11A upon completion ofdrug injection.

FIG. 11C is a side view of the embodiment of FIG. 11B after the needleguard has been extended, concealing the needle.

FIG. 12 is a depiction of an exploded view of the embodiment of FIG.10A.

FIG. 13A is a perspective view of the lower housing of the embodiment ofFIG. 10A.

FIG. 13B is a perspective view of the middle housing of the embodimentof FIG. 10A.

FIG. 14 is a depiction of a partial cross-sectional view of a portion ofthe upper and middle housings of the embodiment of FIG. 10A.

FIG. 15 is a depiction of a latching mechanism of the embodiment of FIG.10A

FIG. 16 is a depiction of another latching mechanism of the embodimentof FIG. 10A.

FIG. 17A is a depiction of a cross-sectional view of a portion of theembodiment of FIG. 10A.

FIG. 17B is a depiction of a perspective view of a portion of the lowerhousing of the embodiment of FIG. 10A.

FIG. 18 is a cross-sectional view of the device of FIG. 10A.

FIG. 19 is an exploded, side view of still another embodiment of thepresent invention.

FIG. 20 is a depiction of a cross-sectional, side view of yet anotherembodiment of the present invention prior to use.

FIG. 21A is a perspective view of an alternative design of the lowerhousing of the embodiment of FIG. 10A.

FIG. 21B is a perspective view of an alternative embodiment of the lowerhousing of FIG. 10A.

FIG. 21C is a cross-sectional view of the lower housing of FIG. 21B.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The following detailed description is to be read with reference to thedrawings in which like elements in different drawings are identicallynumbered. The drawings, which are not necessarily to scale, depictexemplary embodiments for the purpose of explanation only and are notintended to limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention.

The present invention is a drug delivery device, and methods for itsuse, which device overcomes many of the limitations and drawbacks ofconventional syringes and needles as well as auto-injector-type devices.To overcome the drawbacks and limitations of prior devices and toaddress the unfilled needs in the art, embodiments of the presentlydisclosed device and methods include a device that is configured suchthat the user does not see and cannot touch the needle, reducingneedle-phobia and potential for needle contamination. This includesautomatic shielding of the needle after delivery of the drug.

Embodiments of the device have an ergonomic form-factor that permitsoperation one handedly and conveniently allows for alternate siteinjections, such as the leg, arm, or abdomen. In embodiments thatinclude a pressure-sensitive triggering, a needle guard latch inhibitsmovement of the needle. In this manner, the device includes a safetymechanism that will not allow the needle to be exposed if it is notpressed against the injection site.

In FIGS. 1A-1D is illustrated one embodiment of the device of theinvention that includes a window 104 to view the drug prior to use. Acolored indicator may appear in the window after the device has beenused, to provide a visual indication to the user of whether the device'sdrug has been spent. Further, after the drug is delivered, increasedsafety and reduction in the possibility of accidental needle puncturesis provided.

To ensure that the user is aware of the status of the drug delivery andwhether it is completed, this embodiment of the invention includes pawlsand ratchets, such as those illustrated by the pawl 117 and ratchet 116shown in FIGS. 4 and 7 , that engage to produce one or more audibleclicks when the injection is completed. Such a mechanism may signal theuser that the dose has been delivered and the device can be removed fromthe skin, preventing premature withdrawal of the device from theinjection site. Thus, the user actively participates during the entiredelivery process, unlike conventional auto-injectors for which the usermay need to wait several seconds for an assurance that the full dose hasbeen administered.

To provide greater feedback to the user, the disclosed system of pawlsand ratchets also provides audible clicks and motion of the deviceduring delivery to indicate that the injection is progressing. In yetanother embodiment, a louder click at the end of delivery alone or incombination with a visual indicator provides 1 feedback confirming thatthe delivery is completed.

Moreover, the present invention has a friendly, unintimidating designand method of operation, unlike conventional needle safety devices andauto-injectors, which are reminiscent of syringes and discomforting tothe user. Additionally, unlike conventional auto-inserters, the usercontrols insertion of the needle and injection of the drug as describedhereinafter.

In FIGS. 1 through 9 are shown an exemplary device of the of theinvention. In FIGS. 1A through 1D is shown an embodiment of the devicein various stages leading up to injection of the drug and in FIGS. 2Athrough 2C is shown the embodiment during and after injection of thedrug. FIG. 1A shows the device 100 in its pre-use configuration as itmay be received by the user. In this relaxed position, upper housing 101partially overlies the proximal or uppermost portion of lower housing102. In describing the various embodiments of the device, the termproximal is used in relation to the bottom surface of the device. Forexample, in FIG. 1B, proximal is used in relation to bottom surface orbottom 131 of device 100.

As shown, the device's outwardly visible features include upper housing101, lower housing 102, cap 103, window 104, interlock button 105, gripring 106, bottom edge 111 of the upper housing 101 and dose indicator107. FIG. 3 is an exploded view of the components of this embodiment ofthe invention.

A preliminary step in using the device is to remove cap 103, which isremovably attached to lower housing 102, as shown in FIG. 1B. Removingthe cap 103 simultaneously removes needle shield 113 and exposes needleguard 108. Window 104 and needle guard slot 109, each of which arepreferably present on both sides of the device, allow the user to viewand inspect an internally housed syringe 118 and its drug contents.

In use, the device is grasped by placing the palm of the hand over thetop of the upper housing 101, similar to how one grasps a floor-mounted,automotive gear shift. Grip ring 106 provides a visual cue to the useron how to grasp the device. In one embodiment, grip ring 106 is covered,or coated, or made of a suitable elastomeric material including, withoutlimitation, neoprene rubber, urethane, polyurethane, silicone, naturalrubber, thermoplastic elastomer (“TPE”), or combinations thereof toprovide a non-slip and comfortable gripping surface.

The user presses the device, by downward pressure of the palm on gripring 106 and interlock button 105, against the body at the desiredinjection location, typically the top or side of the upper leg, theabdomen, or the side or back of the upper arm. The pressure of the palmon interlock button 105 causes it to deflect downwardly, as shown inFIG. 1C, which in turn unlatches needle guard latch 124, shown in FIG. 5, allowing the needle guard 108 to slide upwardly, and exposing needle110 (note that some device components have been removed from FIG. 5 forillustration purposes). Needle guard latch 124 is formed integrally witha portion of the distal end of upper housing sleeve 120. Upper housingsleeve 120 is a hollow cylinder a portion of which resides in the upperhousing 101 and portion of which resides in lower housing 102 when thedevice is in the relaxed position. Upper housing sleeve 120 is fixedlyattached to upper housing 101 and performs latching functions and actsto trap biasing element 119 against lower housing 102 as described inmore detail below.

Needle guard latch 124 includes inwardly, with respect to thelongitudinal center axis A-A′ of the device, ramped surface 127 and stop130 at its uppermost end. To unlatch the needle guard latch 124, anoutwardly ramped surface 128, complementary to surface 127, that formsthe distal end of interlock button extension 123, engages ramped surface127 on the needle guard latch 124. Engagement of surfaces 127 and 128causes the needle guard latch 124 to deflect outwardly, with respect tothe center axis, removing stop 130 from blocking the upward movement ofneedle guard 108. The latching mechanism and needle guard 108 arepreferably configured so upward movement of needle guard 108 isprevented unless the interlock button 105 is fully depressed. Thisprotects the needle from contamination and damage due to contact withother surfaces, protects the user from accidental needle punctures, andshields the needle from view.

As the user continues to press downwardly on upper housing 101, needleguard 108 moves upwardly, exposing and allowing needle 110 to penetratethe user's skin, stopping when bottom surface 131 of the lower housing102 is substantially flush against the skin. Once needle guard 108passes beyond stop 130, the user may release interlock button 105, orchose not to, without affecting the remaining injection steps. Wheninterlock button 105 is released, resilient member 121, returnsinterlock button 105 to the up position. Movement guide 132 acts toensure that interlock button travels straight up and down.

The needle insertion process described herein gives control of insertionto the user. This feature allows the user to take advantage of acommonly used method often employed by insulin-dependent diabetics: ifthe needle is brought into contact with the skin and held there withoutpiercing the skin, after a few seconds the user will no longer feel thepresence of the needle, at which point the needle can be inserted painfree by increasing the pressure applied to the needle.

After needle 110 has been inserted into the user, the injection processtypically begins, as shown in FIGS. 2A through 2C. With reference toFIG. 6 , a housing latch 122 that is a part of lower housing 102 isshown in close-up detail and prevents the upper housing 101 from movingwith respect to the lower housing 102 in the device's pre-use state(note that some device components have been removed from FIG. 6 forillustration purposes). When needle guard 108 has completed its upwardtravel, ramped surface 133 on needle guard 108 contacts a ramped portionof surface 134 that forms the end of housing latch 122, causing thehousing latch 122 to deflect inwardly, thus allowing the upper housing101 and upper housing sleeve 120 to move downwardly.

After inserting needle 110 into the body, the user maintains pressure onthe upper housing 101. As shown in FIGS. 3, 4, 7 and 8 a plunger rod 115pushes on a plunger 112. Plunger rod 115 is connected fixedly to theupper housing 101 and syringe 118 is secured to or held in a cylinderformed within lower housing 102. Thus, when the upper housing 101 movesdownwardly with respect to and over the lower housing 102, a drug insidethe syringe 110 is delivered through the needle 110 to the patient bythe downward movement of plunger rod 115 and plunger 112 within syringe118.

After the housing latch 122 is disengaged, a biasing element 119 thatsurrounds the distal end of upper housing sleeve 120, is freed from atensioned state to apply a downward force on the upper housing 101 byexerting a downward force on upper housing sleeve 120, which is fixedlyattached, at its uppermost end, to upper housing 101. Biasing element119 also can be used to provide energy for assisting with advancement ofplunger rod 115 and plunger 112 with the user providing additionalrequired force resulting in injection of the drug or the energy suppliedby the biasing element 119 may be sufficient only to advance plunger rod15 and plunger 112. In another embodiment of the present invention,biasing element 119 provides sufficient force to inject the drug,without additional force input required by the user, thus providing aninjection device in which the needle is manually inserted and the drugis automatically injected. The biasing element may be any componentcapable of exerting a downward force on upper housing sleeve 120 to thedegree desired and may be, without limitation, a spring, a compressedgas actuator, a hydraulic drive, a wax actuator, an electrochemicalactuator, a shape memory alloy, and the like and the combinationsthereof. In the embodiment depicted in FIGS. 1 through 9 , the userprovides the additional force required to advance the plunger rod 115and plunger 112 by pressing downwardly on the upper housing 101. Thus,the force required by the user to inject the drug is reduced, in amanner analogous to the way power steering in a car reduces the forcerequired by the driver to turn the steering wheel. Unlike conventionalauto-injectors, the user contributes to the force required for injectionand the present invention provide the user control over the rate ofinjection of the drug.

Referring to FIGS. 4 and 7 , cross sectional views of embodiments of thepresent invention are shown both before and after delivery of the drughas commenced, respectively. As the drug is being delivered, a pawl 117which is attached to upper housing sleeve 120 moves along a ratchet 116that is attached to the lower housing 102. The pawl 117 and the ratchet116 may serve, at least, the following two functions. First, separationof upper housing 101 from lower housing 102 by pulling them apart isprevented. Second, the motion of pawl 117 along ratchet 116 produces asoft clicking noise, providing feedback to the user that upper housing101 is moving and the drug is being delivered. Additionally, and asillustrated in FIG. 8 , at the end of travel of upper housing 101, pawl117 may be configured to engage a deeper recess in ratchet 116, therebyproducing a louder clicking sound, which can provide an audible signalto the user that end of travel has been reached and the drug has beenfully delivered, and further locking the upper housing 101 in place toprevent resetting or reuse of the device.

Referring to FIGS. 2B and 8 , when the drug is completely injected andupper housing 101 is at the end of its travel, bottom edge 111 of upperhousing 101 covers dose indicator 107. Dose indicator 107 is acircumferential, colored ring at the distal portion of lower housing102. This provides a visual cue to the user that the drug delivery hasbeen completed.

Prior to use, the patient can view the drug through window 104 toinspect it for clarity and particulates. After use, the plunger 112 canbe viewed in the window 104, indicating that the device has been used.Alternatively, the window can be designed such that the plunger rod 115as well is visible after the injection is complete. The plunger 112 andthe plunger rod 115 can be brightly colored to provide a clearindication to the patient that the device has been used.

Referring to FIGS. 2C and 9 , after completing the injection, the userremoves device 100 from the skin, and needle guard return element 114causes needle guard 108 to extend over needle 110, protecting the userand others from accidental needle punctures. Needle guard return may beany element capable of causing needle guard 108 to extend over needle110 including, without limitation, a spring, a compressed gas actuator,a hydraulic drive, a wax actuator, an electrochemical actuator, a shapememory alloy, and the like and the combinations thereof. Once needleguard 108 is fully extended, a needle guard lock 125 engages a slot inneedle guard 108, preventing the needle guard 108 from retracting.Needle guard lock 125 is a cantilever latch extending inwardly from theinner surface of upper housing sleeve 120. Lower housing rib 126, a partof the lower housing 102, may be configured to prevent the needle guardlock 125 from engaging the slot in the needle guard 108 prematurelyduring delivery by blocking the slot. In another embodiment of thepresent invention, needle guard 108 may extend and lock in place ifdevice 100 is removed before delivery is complete, to prevent reuse, orsharing of the device.

With the assisted delivery approach offered by the present invention,the user is actively engaged during the entire delivery process. This isdistinguishable from the activation process for conventionalauto-inserters, in which after pressing the button, the user passivelywaits, for several second, for the drug to be delivered, sometimeswondering whether the injection is in process or not.

The assisted activation approach of the present invention has theadditional advantage that it reduces development time and costassociated with modifying the injection device for delivering differentdrugs because the user controls delivery speed by varying the forceapplied to the upper housing 101. If the plunger is slightly stuck, theuser can apply a little more force, unlike conventional auto-injectorsthat must be designed for worst case force requirements, that varydepending on the drug, cartridge, plunger, needle, and friction in themechanism.

In another embodiment, the interlock button 105 and the interlock spring121 can be omitted from the design. In this embodiment, the upperhousing 101 is free to move downwardly before hitting a stop. Thismovement is used to unlock the needle guard 108 using a mechanismsimilar the interlock mechanism described above, allowing the needleguard 108 to retract. Once the needle guard 108 is fully retracted, itmay disengage another latch that allows the upper housing 101 todiscontinue moving downwardly and inject the drug in a similar manner asis described above.

In FIGS. 10 through 18 is depicted yet another embodiment of theinvention. In FIG. 10A is shown device 200 with upper housing 205, lowerhousing 202 and middle housing 201 therebetween. Upper housing 205includes grip cap 228. In the relaxed position, upper housing 205partially overlies the proximal, portion of middle housing 201. Thedistal-most portion of middle housing 201 is fixedly seated in lowerhousing 202. Also shown in FIG. 10A are upper housing bottom edge 211,travel ridge 216, and window 204. Window 204 preferably is seated withinthe proximal portion of lower housing 202. A second window, not shown,preferably is present on the device on the side opposite of window 204.

Cap 203 is removably attached to lower housing 202 and, in FIG. 10B, isshown removed from device 200 to expose needle shield 213, needle shieldclamp 217 and needle guard 208. During removal of cap 203, needle shieldclamp 217 grabs and simultaneously removes needle shield 213 exposingneedle guard 208 to the user. When the device user presses the needleguard 208 against the skin, this action causes needle guard 208 to slideupwardly exposing needle 210, as shown in FIG. 10C.

FIG. 12 is an exploded view of device 200. Grip cap 228 includes gripcap assembly pins 230 that fixedly secure grip cap 228 on upper housing205. Assembly pins 230 mate with holes 242 in upper housing 205.Preferably, assembly pins 230 are square in cross-section with roundedcorners providing an interfering surface between the corners of assemblypins 230 and holes 242. Guides 233 and plunger rod 215, which areintegral with and extend downwardly from the inner surface of grip cap228 as shown. Plunger rod 215 includes a damper 221 at its distal end.Also shown are syringe 218 with plunger 212 and needle shield 213.

In a preferred embodiment, the external surface of grip cap 228 iscoated with or formed from, or the entirety of grip cap 228 is formedfrom, a material capable of providing a soft, non-slip grip for theuser. Suitable materials for coating or forming the grip cap include,without limitation, elastomeric materials such as neoprene rubber,urethane, polyurethane, silicone, natural rubber, TPE and the like andcombinations thereof.

Upper housing 205 includes click latch 220, handle rib guide 238, andbottom edge 211. For click latch 220, as well as the other latches usedin the device, preferably at least two latches are used and the samelatches are symmetrically positioned with respect to each other tofacilitate smooth movement and operation of the device.

Middle housing 201 is shown in FIG. 12 with body 207 and handle guideslots 239 on the external surface of the proximal portion of body 207.When the device is in use, handle rib guides 238, which are an integralpart of upper housing 205, engage with and slide within handle guideslots 239, maintaining smooth and controlled motion of upper housing 205during drug delivery.

Body 207 may serve as a dose indicator because, as the device isactivated, upper housing 205 descends over body 207. When the completemedication dose has been delivered, body 207 is fully obscured by upperhousing 205 as shown in FIG. 11C. Preferably body 207 is colored, morepreferably with a bright color, or is patterned to provide easily viewedvisual feedback to the user that the dosing is progressing or has beencompleted. Optionally, a scale may be included on body 207 to visuallyquantify the amount of drug that has been delivered or remains to bedelivered.

With reference to FIG. 13 , middle housing 201 also includes griplatches 224, click latch capture slots 236, and needle guard latch 237.Grip latch 224 is a generally rectangular element movably attached atits distal-most portion to the inner surface 243 of middle housing 201so that it is capable of movement outwardly toward inner surface 243upon application of force. Grip latch 224 also includes a stop surface245 and a triangular shaped stop 244 extending inwardly toward thedevice's center from one corner of its topmost portion. In the device'sresting, pre-use position grip latch 224 prevents upper housing 205 frommoving with respect to middle housing 201 due to stop 245 interferingwith the downward travel of guides 233 of grip cap 228.

With reference to FIGS. 12 and 13 , lower housing 202 is shown withlower housing base 206, end of travel ridge 216, window 204, housinglatch 229, guide slots 227 and syringe retainer clip 235. Cap 203removably attaches to lower housing base 206 via cap retainer ring 234.In use, lower housing base 206 contacts the user's skin and, thus,preferably is made of any of the soft flexible materials suitable foruse for grip cap 228.

Window 204 provides an opening in lower housing 202 for viewing of thecontents of syringe 218. Window 204 is positioned such that the bottomof syringe 218 is visible to the user allowing the user to verify thatplunger 212 has reached the end of its travel to the bottom of thesyringe. Window 204 may be any convenient size and shape and preferablyis oblong in shape with its long axis aligned with the long axis of thedevice and syringe so that the desired length of the syringe is exposedto view.

Guide slots 227 maintain the alignment of three different components:guides 233 of grip cap 228; grip latch release 231; and needle guardextensions 241. Guide slots 227 ensure smooth activation of the deviceby maintaining alignment and vertical travel of upper housing 202 andneedle guard 208 and reliable latching and unlatching of grip latch 231.Housing latch 229 extending outwardly secures middle housing 201 tolower housing 202 by engaging a recess, that is not shown, in innersurface 243 of middle housing 201. In non-reusable embodiments of thedevice, the shape of latch 229 and the recess are such that the middleand lower housing cannot be separated. For reusable embodiments, therecess and latch are configured to enable the middle and lower housingto be pulled apart.

Referring to FIG. 12 , needle guard 208 includes needle guard slot 209formed on one side by grip latch release 231 and the other side byneedle guard extension 241. Grip latch release 231 includes rampedsurface 240. Referring to FIGS. 14 and 15 , ramped surface 240 of griplatch release 231 faces outwardly and, as grip latch 231 travelsupwardly, engages ramped surface 244 of grip latch 224, which facesinwardly, causing grip latch 224 to deflect outwardly, removing theobstruction to the downward movement of guide 233 and 205.

Needle guard slot 209 permits window 204 to be used to view the syringeand plunger as the plunger acts on the syringe at the end of theplunger's downward stroke. Additionally, needle guard return 214 lieswithin and at the bottom of a space formed by grip latch release 231 andneedle guard extension 241.

An inventive aspect of the device 200 is the way in which syringe 218 issuspended inside the device. With reference to FIGS. 12, 13, and 17 ,syringe 218 is held between needle shield 213 and damper 221, each ofwhich are flexible components, to protect syringe 218 in the eventdevice 200 is dropped or otherwise mishandled. When the device isassembled, syringe 218 is loosely held within cavity 246 of lowerhousing 202 by retainer clips 235. Depending on the volume of medicationwithin syringe 218, when the device is in used, there may be some travelof upper housing 205 before damper 221 contacts plunger 212 and, duringthis initial downward travel, damper 221 acts as an air piston tocompress the air in the gap formed between the end of plunger rod 215and plunger 212, which provides a rate-dependent resistance to motion tothe initial downward motion of grip. When damper 221 moves fast, aircannot escape quickly enough to reduce the build-up of air pressure.Damper 221 may optionally include through-holes, that are not shown,therein to allow air to leak past damper 221. Alternatively, afriction-based resistance from the damper without pressure build-up, usea damper in which there is no leak and no rate dependence, orcombinations thereof may be used. Upon contact of damper 221 withplunger 212, damper 221 collapses inwardly towards plunger rod 215reducing the friction between damper 221 and the inside surface ofcavity 246.

With reference to FIGS. 10 and 11 , when the user desires to use device200, the user removes cap 203 from lower housing 202, which actionsimultaneously removes needle shield 213 and exposes needle guard 208.The user grasps device 200 by upper housing 205, places the palm of thehand over grip cap 228 and presses downwardly on grip cap 228 whileholding the device 200 against the desired injection site on the body,which pressing action causes needle guard 208 to slide upwardly exposingneedle 210. Continuing application of pressure to grip cap 228 resultsin needle 210 penetrating the user's skin and sub-dermal tissue,stopping when lower housing base 206 contacts the skin surface or whenthe rim 245 reaches of needle guard 208 reaches the end of its travelwithin lower housing 202.

With reference to FIG. 15 , when needle guard 208 reaches the end of itsupward travel within lower housing 202, ramped surface 240 of grip latchrelease 231 contacts the oppositely facing and complementarily rampedsurface 244 of grip latch 224 of middle housing 201 causing grip latch224 to deflect towards the inner wall 243 of middle housing 201. Thisaction removes stop surface 245 of grip latch 224 from interfering withthe downward travel of guide 233 of grip cap 228 freeing guide 233 andallowing upper housing 205 to move downwardly and over middle housing201.

When upper housing 205 moves downwardly, the medication inside ofsyringe 218 is delivered through needle 210 as plunger rod 215 anddamper 221 of grip cap 228 push downwardly on syringe plunger 212. Atthe end of the medication delivery, body 207 is substantially completelycovered by upper housing 205 and bottom edge 211 of upper housing 205has mated with the complementarily shaped travel ridge 216 of lowerhousing 202. Also, plunger rod 215, damper 221, and plunger 212 areclearly visible within window 204. All of these features provide theuser with visual confirmation that the drug has been delivered and thehard stop of bottom edge 211 against travel ridge 216 provides a tactileconfirmation to the user.

Additionally, a click mechanism is activated at the end of drug deliveryto provide audible feedback. With reference to FIG. 14 , click latch 220is deflected outwardly when ramp 247 thereof contacts and slides pastthe top of middle housing 201. When the ramp 247 moves sufficiently fardownwardly, ramp 247 aligns with click latch capture slot 236 and theramp 247 slips into capture slot 236, which slot extends through thewall at the proximal portion of middle housing 201, and snaps againstthe outer surface of body 207 of middle housing 201 creating a clickingsound. In non-reusable versions of the device, click latch 220 ispermanently captured by capture slot 236 and cannot be reset. In apreferred embodiment, two click latches 220 are positioned at positions180 degrees opposite of each other in order to provide smooth activationof the device and to enhance the clicking and latching functions.

As the user removes device 200 from the skin, needle guard return 214,shown in FIG. 12 as a spring, that was compressed by pressing of device200 against the user's skin, expands causing needle guard 208 to extenddownwardly over needle 210 protecting the user from accidentalpunctures. In addition to a spring, the needle guard return may be acompressed gas actuator, a hydraulic drive, a wax actuator, anelectrochemical actuator, a shape memory alloy, and the like and thecombinations thereof. When needle guard 208 is fully extended, needleguard retainer 232 engages stop 248, shown in FIG. 13 , on lower housing202 preventing needle guard 208 from separating from lower housing 202.In FIG. 16 is shown needle guard latch 237 movably attached at itsdistal end to the inner surface 243 of middle housing 201. When needleguard 208 is upwardly traveling, needle guard latch 237 is deflectedoutwardly on contact with the outer surface of guide 233 or of needleguard extension 241. When needle guard 208 travels downwardly andextends to cover needle 210, needle guard latch 237 slips over the topof needle guard extension 241 preventing needle guard 208 from againretracting.

Prior to use, extension guides 233 of grip cap 228 retain needle guardlatch 237 in an outwardly deflected position allowing needle guard 208to retract for insertion of needle 210. Two needle guard retainers 232and needle guard latches 237 preferably are used and are located 180degrees apart around the central axis of the device 200. If the device200 is removed from the skin before delivery of medication is completed,needle guard 208 will extend to cover needle 210 and locks to preventreuse of the device. In an alternative, reusable embodiment, needleguard 208 extends, but does not lock in place in the event device 200 isremoved from the skin before delivery of medication is completed.

FIG. 19 is a depiction of an alternative, reusable embodiment of device200 in which upper housing 205 and middle housing 201 are separable fromlower housing 202. In this embodiment, the user separates the middle andlower housings, inserts syringe 218 into the lower housing and thenreattaches the middle and upper housings.

In FIG. 20 is depicted yet another alternative embodiment of device 200in which an assist drive 219 is included. Assist drive 219 may find itsgreatest utility in delivering viscous drugs. The assist drive 219applies a force between upper housing 205 and middle housing 201exerting a downward force on upper housing sleeve 120. This reduces theamount of downward force the user must apply to grip cap 228 in order toinject the drug. Assist drive 219 may be a spring, a compressedactuator, a hydraulic drive, a wax actuator, an electrochemicalactuator, a shape memory alloy or the like or combinations thereof.Alternatively, assist drive may provide sufficient force to inject thedrug, without additional force input required by the user, thusproviding an injection device in which the needle is manually insertedand the drug is automatically injected in a manner similar to aconventional auto-injector.

In FIG. 21 is depicted an alternative embodiment of lower housing 202 ofdevice 200 in which a resettable clicking mechanism for a reusabledevice is included. In this embodiment, guide slots 227 engage guide2225 of clicker 222. Clicking device 222 is biased by needle guardreturn 214. To set clicking device 222, the user presses down on one ofclicker guides 225 until clicker latch 226 extends over clicking device222 holding it down. When grip cap 228 moves downwardly, at the end oftravel, guide 233 contacts a ramped surface on clicker latch 226 causingit to deflect inwardly and releasing clicker 222 to travel upwardlyunder the force of needle guard return 214. A click sound is generatedwhen click surface 223 of clicker 222 contacts lower housing 202signaling that the drug has been completely delivered. The compressingof needle guard return 214 is increased when needle guard 208 isretracted during injection of the drug, increasing the force applied tothe clicking device and the volume of the click sound. Alternatively,the click mechanism can be reset automatically when the user attachesthe upper housing to the lower housing upon loading a new syringe intothe device.

Additional embodiments of the present invention can be envisioned, butare not included in the attached figures. This includes a multiple-dosedesign in which one or both of the upper and middle housings rise to apartial height and deliver a partial syringe when depressed by the user.

What is claimed is:
 1. A method of injecting a medication from amedication delivery device of the type including an upper housing, alower housing, a syringe supported by the lower housing and having aneedle, and a needle guard supported by the lower housing, the methodcomprising the steps of: placing the medication delivery device againsta skin surface so as to cause the needle guard to abut the skin surface,wherein the upper housing is releasably locked with respect to movementtoward the needle; applying a force against the upper housing along aninsertion direction, thereby causing the skin surface to force theneedle guard to retract relative to the lower housing and thereby exposethe needle so as to insert the needle through the skin surface, whereinthe applying step causes the needle guard to unlock the upper housingwith respect to movement toward the needle, thereby allowing movement ofthe upper housing toward the needle; and after the unlocking step,continuing to apply the force against the upper housing along theinsertion direction, thereby causing the upper housing to move towardthe needle, thereby driving a medication contained within the syringeout the needle.
 2. The method of claim 1, wherein the continuing stepfurther comprising the step of driving a plunger rod into the syringe soas to drive the medication out the needle.
 3. The method of claim 1,wherein the medication delivery device includes a latch that interfereswith the upper housing so as to releasably lock the upper housing withrespect to movement toward the needle, and the unlocking step comprisescausing the needle guard to contact the latch and bias the latch awayfrom the upper housing to thereby unlock the upper housing.
 4. Themethod of claim 1, further comprising moving the medication deliverydevice away from the skin surface along a direction opposite theinsertion direction so as to remove the needle from the skin surface. 5.The method of claim 4, wherein the moving step further comprises causingthe needle guard to advance relative to the needle so as tosubstantially encapsulate the needle.
 6. The method of claim 5, whereinthe moving step further comprises preventing the needle guard fromretracting with respect to the needle.
 7. The method of claim 1, furthercomprising the step of, after the continuing step, preventing the upperhousing from retracting away from the needle.
 8. The method of claim 1,wherein the upper housing is unlocked with respect to movement towardthe needle as the needle guard completes its travel relative to thelower housing.
 9. The method of claim 1, wherein the medication deliverydevice further includes a middle housing coupled between the upperhousing and the lower housing.
 10. A method of injecting a medicationfrom a medication delivery device of the type including an upperhousing, a lower housing, a syringe supported by the lower housing andhaving a needle, a needle guard supported by the lower housing, and amiddle housing coupled between the upper housing and the lower housing,the method comprising the steps of: placing the medication deliverydevice against a skin surface so as to cause the needle guard to abutthe skin surface, wherein the upper housing is releasably locked withrespect to movement toward the needle; applying a force against theupper housing along an insertion direction, thereby causing the skinsurface to force the needle guard to retract relative to the lowerhousing and thereby expose the needle so as to insert the needle throughthe skin surface; during the applying step, unlocking the upper housingwith respect to movement toward the needle, thereby allowing movement ofthe upper housing toward the needle; and after the unlocking step,continuing to apply the force against the upper housing along theinsertion direction, thereby causing the upper housing to move towardthe needle, thereby driving a medication contained within the syringeout the needle.
 11. The method of claim 10, wherein the continuing stepcomprises the step of progressively covering a body of the middlehousing with the upper housing to thereby provide a visual indicationthat the medication is being delivered.
 12. The method of claim 11,wherein the progressively covering step further comprises substantiallycompletely covering the middle housing with the upper housing so as toindicate that the medication has been fully delivered.
 13. The method ofclaim 10, wherein the continuing step further comprising the step ofdriving a plunger rod into the syringe so as to drive the medication outthe needle.
 14. The method of claim 10, wherein the medication deliverydevice includes a latch that interferes with the upper housing so as toreleasably lock the upper housing with respect to movement toward theneedle, and the unlocking step comprises causing the needle guard tocontact the latch and bias the latch away from the upper housing tothereby unlock the upper housing.
 15. The method of claim 10, furthercomprising moving the medication delivery device away from the skinsurface along a direction opposite the insertion direction so as toremove the needle from the skin surface.
 16. A method of injecting amedication from a medication delivery device of the type including anupper housing, a lower housing, a middle housing that includes a bodythat is exposed between the upper housing and the lower housing, and asyringe supported by the lower housing and having a needle, the methodcomprising the steps of: placing the medication delivery device againsta skin surface; moving the medication delivery device toward the skinsurface along a direction to thereby cause the needle to penetrate theskin surface; and applying a force to the upper housing along thedirection to thereby move the upper housing along the middle housingbody toward the needle such that the upper housing progressively coversthe middle housing body as the upper housing moves toward the needle tothereby provide a visual indication that medication contained in thesyringe is being delivered.
 17. The method of claim 16, wherein theapplying step comprises moving the upper housing along the middlehousing body until a first surface of the lower housing mates with acomplimentary second surface at a distal end of the upper housing. 18.The method of claim 17, further comprising causing a tactile feedbackwhen the first surface mates with the corresponding second surface. 19.The method of claim 16, wherein the placing step comprises placing themedication delivery device against a skin surface so as to cause theneedle guard to abut the skin surface, wherein the upper housing isreleasably locked with respect to movement toward the needle.
 20. Themethod of claim 19, wherein the moving step comprises applying a forceagainst the upper housing along the direction to thereby cause the skinsurface to force a needle guard supported by the lower housing toretract relative to the lower housing and expose the needle so as toinsert the needle through the skin surface.